LI77645: INFINITE LOOP WITH -QSMP

XL C/C++ for Linux Fix Pack 8 (October 2015 Update) for 12.1
XL C/C++ for Linux Fix Pack 4 (October 2013 Update) for 12.1
XL C/C++ for Linux Fix Pack 5 (December 2013 Update) for 12.1
XL C/C++ for Linux Fix Pack 6 (February 2014 Update) for 12.1
XL C/C++ for Linux Fix Pack 7 (May 2014 Update) for 12.1

APAR status

• Closed as program error.

Error description

• Compiling the following test case with -qsmp=omp will result in
  runtime application infinite loop for the do while statement.
  
  #include <stdio.h>
  int main ()
  { printf ("hello\n");
    unsigned char dividend = 0;
    do {
      printf ("dividend = %x\n", dividend);
    } while (++dividend);
    printf ("good bye\n");
    return 0;
  }
  
  xlc_r -qsmp=omp t.c
  
  ===== ACTUAL OUTPUT:
  Prints out dividend, iterating through the unsigned char hex
  values, non-stop and "good bye" is not printed out.
  .....
  dividend = fd
  dividend = fe
  dividend = ff
  .....
  
  ===== EXPECTED OUTPUT:
  .....
  dividend = fd
  dividend = fe
  dividend = ff
  good bye
  

Local fix

• Use -qstrict_induction
  

Problem summary

• PROBLEM DESCRIPTION: Integer overflow for loop induction
  variable causes incorrect output during loop normalization
  
  USERS AFFECTED: Users explicitly overflowing the loop induction
  variable at -O3, -qsmp, -qhot, -qpdf, or -qipa
  

Problem conclusion

• Problem is fixed. Apply provided service.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IV37088

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL C/C++ FOR LI

• Fixed component ID

  5725C7300

Applicable component levels

• RC10 PSN IV37088

     UP06/09/13